This invention relates to adjustment and locking mechanism for vehicle seats. More particularly, this invention relates to such mechanisms for walk-over seats like the type used in railroad passenger cars.
Many types of vehicles have seats in which the seat back is movable from a first position to a second position. For example, two-door automobiles have seats whose seat backs are moved forward to allow a passenger to enter the rear of the passenger compartment to sit on the rear seat. Also, railroad cars have so-called "walk-over" seats. In a walk-over seat, the seat back faces a first direction when the railroad passenger car is traveling in a first direction. Instead of turning around the railroad car when the train travels in opposite, second direction, the seat backs of the railroad car seats are merely moved to a second position so that they face the second direction of travel. The train conductor typically walks down the aisle of the railroad passenger car and pushes the seat backs over to their second position.
One problem with movable seat backs is that the seat back may move forward upon rapid deceleration of the vehicle. Such rapid deceleration may occur, for example, during heavy braking or as a result of an impact between the vehicle and another object. The forward movement of the seat back under such conditions is typically caused by a force being applied to the back side of the seat back in the direction of travel.
Numerous latching and locking mechanisms are known to prevent the seat back from moving forward upon rapid deceleration of the vehicle. Some of the prior art latching mechanisms have a lever that locks the seat back into place. The use of such a lever, however, is undesirable in walk-over seats because the train conductor cannot simply walk down the aisle and move the seat backs. He must disengage each lever of each seat to move the seat back to the second position.
To overcome this disadvantage, several prior art locking mechanisms operate using the inertia of one or more members within the locking mechanism. For example, U.S. Pat. No. 3,897,101 to Hess discloses an inertial rack and pawl system in which two identical side-by-side systems control movement of the seat back. U.S. Pat. No. 2,660,222 to Woodsworth uses the inertial movement of a pendulum to prevent seat back movement during rapid deceleration.
These and other prior art systems are often very complex, and are expensive to manufacture since they contain parts that cannot be readily stamped out of metal.